A review of cellular automaton fluids, which are the class of cellular automata used in describing fluids. Cellular automaton fluids are discrete analogs of molecular dynamics in which the particles have discrete velocities and move on the sites of a lattice according to some rule of evolution. Two-dimensional fluids are considered, with some comments regarding models for fluids in 3 dimensions. Analytical and numerical simulation results, including some on the wake behind a cylinder, are discussed for the 2-dimensional cellular automaton (CA) models. Some issues are discussed that need resolution before the models can be used in practical simulations.